Process for oxidizing primary amines to oximes by elemental oxygen

Abstract

Primary saturated aliphatic and alicyclic amines are oxidized by elemented oxygen to oximes, especially cyclohexylamine to cyclohexanone oxime, in vapor phase using silica gel catalyst; preferably using concentrations by volume such as 1% to 5% of amine and 5% to 30% of oxygen, and using temperatures between about 120° C. and 250° C. at atmospheric pressure.

I claim: 
     
       1. Process for conversion of primary saturated aliphatic and alicyclic amines having between 2 and 12 carbon atoms in the molecule to oximes, comprising contacting said amine in vapor phase with elemental oxygen and with essentially only unreactive diluent vapors or gases at amine concentration and oxygen concentration outside the explosive limits; and with a silica gel catalyst having surface area of between about 50 and about 1000 m 2  /g; at absolute pressure between about 10 and 1,000 kPa; and at temperature between about 120° C. and about 250° C.; and at contact time of the heated gaseous reactants with the catalyst between about 0.1 and 10 seconds. 
     
     
       2. Process of claim 1 wherein said silica gel catalyst has a surface area at least about 100 m 2  /g. 
     
     
       3. Process of claim 2 wherein said silica gel catalyst has a surface area between about 200 and about 600 m 2  /g. 
     
     
       4. Process of claim 1 wherein the amine is alicyclic. 
     
     
       5. Process of claim 4 wherein the amine is cyclohexylamine, the amine concentration is between about 0.5% and 6% by volume, the oxygen concentration is between about 5% and 23% by volume, the pressure is about atmospheric, the temperature is between about 135° C. and 175° C., the contact time of the heated gaseous reactants with the catalyst is between about 2 and 8 seconds and the catalyst has average pore diameter of about 10 nm and surface area of about 350-500 m 2  /g.